Example applications of air-conditioning apparatuses include multi-air-conditioning apparatuses designed for buildings. In these air-conditioning apparatuses such as multi-air-conditioning apparatuses designed for buildings, typically, a heat source unit is provided with an air-sending device to send air to a heat exchanger. This air-sending device is, for example, a propeller fan. Air is sent to the heat exchanger by the propeller fan. This propeller fan is often installed in an upper part of the heat source unit. If a propeller fan is installed in an upper part of the heat source unit in this way, the resulting distribution of air velocity is such that the air velocity is high in the upper part of the heat exchanger, with the air velocity progressively decreasing toward the lower part of the heat exchanger. This tends to result in deteriorated air velocity balance for the heat source unit. During heating operation, this unbalance of air velocity leads to a decrease in evaporating capacity in the lower part of the heat exchanger where the air velocity is low, resulting in increased frost formation on the lower part of the heat exchanger. This may give rise to a risk that the frost deposited on the lower part of the heat exchanger is not completely melted during defrosting operation.
In order to address this problem, Patent Literature 1 discloses an air-conditioning apparatus including a subcooling heat exchange unit provided in a lower part of a heat exchanger. Patent Literature 1 aims to reduce the amount of frost deposited on the lower part of the heat exchanger through the provision of the subcooling heat exchange unit.